Twitter helped Met to save Olympic venues

A planned attack by rioters on the London Olympic site was foiled after Met detectives intercepted Twitter and BlackBerry messages about the plot, it was revealed today.

Met assistant commissioner Lynne Owens told MPs that police were deployed to protect the Games venues after officers monitoring social networking activity found evidence that they were about to be targeted by rioters.

The revelation came as the Met also disclosed that up to one in four of the rioters arrested in London so far is a gang member, and Home Secretary Theresa May raised the prospect of entire areas being placed under curfew to prevent future disturbances.

Ms Owens's comments came as she appeared before the Commons home affairs select committee at a special hearing in Westminster on the policing of the riots.

She told MPs that the Met had been monitoring Twitter and the BlackBerry messaging system, known as BBM, and had been able to prevent several key sites around London, including the Olympic Park, being attacked.

"On that night through Twitter and BBM there was intelligence that the Olympic site, Westfields and Oxford Street were going to be targeted," she said. "We were able to secure all those places and indeed there was no damage at any of them. We were able to respond because of our monitoring of Twitter and BBM."

Today acting Met commissioner Tim Godwin announced that an analysis of the backgrounds of riot suspects detained so far showed that about "20 to 25 per cent" were "gang affiliates".

His comments, which come a day after Prime Minister David Cameron pledged to wage "war" on gangs, are the strongest indication so far of the extent to which gangs were involved in fomenting last week's violence.

Revealing the new figures on gang involvement in the rioting, Mr Godwin said that while the statistics were provisional, an early assessment had shown significant participation by gang members.

Met research has estimated that about 170 gangs operate in London. Police believe gangs also helped to organise some of the initial rioting in Tottenham and the subsequent disturbances elsewhere. Witnesses have reported seeing younger gang members carrying looted televisions and other goods to gang leaders waiting in cars nearby.

Mrs May vowed to support police if they adopted more robust tactics to deal with any future disorder. She also announced that ministers would consider plans to introduce new curfew powers which would bar whole communities, rather than just individuals, from going out at night. The powers could be extended to juveniles.

In a swipe at police leadership, Mrs May also said that too many chief constables had been assessed on "whether they ticked boxes" and hit government targets and that she now wanted to see "single-minded crime fighters" running forces instead.

She added that the need to appoint a new Met Commissioner swiftly, with the Olympics looming, meant that there was no time to rewrite the law to allow overseas police chiefs such as Bill Bratton to apply and insisted that she was convinced that a "tough crime fighter" from Britain could be found to lead the Met.

The Home Secretary also said new guidance on handling riots would be drawn up by HM Chief Inspector of Constabulary, Sir Denis O'Connor, to ensure that police are able to respond more effectively to future disorder.